The present invention is directed to a hand belt sander. More particularly, it relates to a hand belt sander which has a housing for receiving a motor, a drive roller and a deflecting roller, an endless sanding belt guided along the deflecting roller and over a sanding plate, and a guide plate which has a control plate with a fork-shaped end for receiving the deflecting roller and arranged to be displaceable with the latter.
A hand belt sander of the generic type comprising drive and deflecting rollers and an automatic belt running centering means is described in EP-PS 7172. A feeler with a lever system for swiveling the deflecting roller is supported at the housing of the known hand belt sander. The support is located near the deflecting roller.
Hand belt sanders have the peculiarity that the circulating sanding belt wanders laterally, depending on the force and direction of application. The belt running centering means is provided in order to ensure that the center of the sanding belt accurately conforms to the center of the drive or deflecting roller running surface. As soon as the sanding belt moves transversely relative to the running direction, one of its edges strikes the feeler which is situated a short distance therefrom. The feeler acts on the deflecting roller via the lever system. The deflecting roller is moved out of the position in which it is parallel to the axis of the drive roller in such a way that the belt is steered again into the center of the roller circumference.
Disadvantages of the known belt running centering means consist in its costly construction which comprises a plurality of articulations and is susceptible to disturbances from vibration and dirt, as well as the high wear on the lever system for the belt running centering means and on the sanding belt to be centered. A further disadvantage consists in the necessary adjustment of the known belt running centering means depending, for example, on elongation of the sanding belt caused by wear or as a result of the differences in length between different sanding belts when exchanging the latter.